Scatterings

Random Scattered Photons Can Be Coordinated

Yvonne Carts-Powell

Particles threading a maze provide a metaphor for the way that photons travel through the medium by random scattering.

The wave nature of light is important for understanding how photons emitted in a complex disordered structure can mutually coordinate their paths. David Garcia and others at the Niels Bohr Institute at the University of Copenhagen (Denmark) recently showed that photons emitted by a quantum dot, embedded in a disordered photonic crystal (Phys. Rev. Lett. 109, 253902).

The emitters probe in situ the microscopic details of the medium, and imprint such near-field properties onto the far-field correlations. Thus, although light scattering is a random process, different paths can be correlated encoding information about the medium.

Particles threading a maze provide a metaphor for the way that photons, emitted from a light source in the center of a complex medium, travel through the medium by random scattering. The photons take different paths but are interdependent in the sense that that the chance of observing a photon at one outlet is increased if a photon is observed at the other outlet.

Garcia explains, “The photons are scattered in all directions … But photons are not just light particles, they are also waves, and waves interact with each other. This creates a link between the photons and we can now demonstrate in our experiments that the photons’ path through the material is not independent from the other photons.”